At present, the robot spraying technology is increasingly widely applied in the automobile hub spraying field. In the traditional production mode of spraying robots, one robot is equipped with one spray gun, hubs to be sprayed need to be classified according to the types of sprayed paints and are collectively fed, i.e., produced in batch; when needing to spray a next hub colored paint, the colored paint must be replaced. In the traditional production mode, the equipment efficiency is reduced, and massive in-process is caused by the batch feeding mode. Under current market demands for progressive small batch and customization, the traditional spraying mode already cannot meet the requirements of flexible production, so a production mode and equipment for flexible spraying are urgently needed.